This invention relates to intervertebral implants; and more specifically, it relates to new and improved instruments and methods for preparing an intervertebral space for receiving an artificial intervertebral disc implant (sometimes referred to below simply as an implant).
When it is necessary to completely remove a disc from between adjacent vertebrae, the conventional procedure is to fuse the adjacent vertebrae together. More recently, there have been important developments in the field of disc replacement, namely disc arthroplasty. Disc arthroplasty involves the insertion of an artificial intervertebral disc implant into the intervertebral space between adjacent vertebrae, thereby allowing limited universal movement of the adjacent vertebrae with respect to each other.
Some instruments have been developed to date for preparing an intervertebral space for receiving an artificial disc implant. These instruments include a set of different sizes of trial implants, different ones of which are inserted into a cleaned out intervertebral space until the correct size trial implant has been determined, thereby determining the size of the actual implant to be inserted. The trial implant may have a fixed stop member in the form of a pin fixed to the rear end of the trial implant and extending vertically for engaging the vertebrae to limit movement of the trial implant into the intervertebral space. Some implants have a raised keel which requires that a cutout or slot be formed in the vertebrae adjacent the intervertebral space for receiving these raised keels. One known arrangement for forming these cutouts is a chisel which can be mounted with chisel portions movable along guiding slots in the top and bottom of the selected trial implant as the chisel portions cut into the adjacent vertebrae to form the two cutouts.
One known artificial disc implant is shown in Published application No. WO 01/01893, published Jan. 11, 2001, and instruments for inserting same are shown in Published application No. WO 01/19295, published Mar. 22, 2001. Another disclosure of artificial disc implants and apparatus associated therewith is contained in U.S. Ser. No. 10/423,879 filed Apr. 28, 2003. The teachings of these three references are hereby incorporated by reference.
While these known instruments and methods represent a substantial improvement in the art, there exists a continuing need for improvements in the field of instruments and methods for preparing an intervertebral space for receiving an artificial intervertebral disc implant.